Many pharmaceutical products or drugs that provide relief from nasal or lung ailments are delivered through the respiratory system. In order to deliver these drugs, typically, the drug is compressed in a container. Users release the compressed pharmaceutical by opening a valve for a brief interval of time near the user""s mouth or nose. Pump mechanisms may also be used to directly spray the pharmaceutical into the user""s mouth or nose. The user may then draw a breath to further inhale the pharmaceutical product.
These techniques for delivering pharmaceuticals pose several problems. The first problem is that the droplet size produced is typically too large to be carried in an air stream generated by a normal intake of breath. Thus, in order to transport the larger droplets of pharmaceutical products, the product is propelled into the orifice. This may be done by using compressed air or by expelling the pharmaceutical product into the orifice at a high speed.
Unfortunately, a fast moving particle, defined as a particle that is moving much faster than the accompanying airstream, cannot easily travel around bends that occur in the human respiratory system. Thus, when the traditional means of injecting pharmaceuticals into the mouth are used, much of the pharmaceutical product is deposited on the back of the mouth or in the throat. The deposited pharmaceutical product may then be ingested into the digestive tract instead of the respiratory system. The ingested pharmaceutical product represents lost or wasted medication.
A second problem is that the varying amounts of lost pharmaceutical product makes it difficult to control dosages. Wasted droplets of medication that are deposited on the back of the throat make it possible that the patient will receive insufficient medication Determining the amount wasted and trying to compensate for the wasted medication is a difficult and inexact process.
Thus an improved method and apparatus of delivering pharmaceutical products to a patient""s respiratory system is needed.
An inhaler that uses capillary effects to output droplets of pharmaceutical product is described. The inhaler includes transducers and lenses to generate focused acoustic waves in a reservoir of pharmaceutical product. The frequency and pulse width output of the transducers are set to cause capillary action in the pharmaceutical product. The capillary action results in the ejection of small droplets of pharmaceutical product at low frequencies. The low frequencies used allow more flexibility in the design of the inhaler.